- Books Name
- class 7 Mathematics Book
- Publication
- ReginaTagebücher
- Course
- CBSE Class 7
- Subject
- Mathmatics
Chaper-9
Rational numbers
Rational numbers on number line
Rational numbers and integers
Natural Numbers
All positive integers like 1, 2, 3, 4……..are natural numbers.
Whole Numbers
All natural numbers including 0 are whole numbers.
Integers
All negative and positive numbers including 0 are called Integers.
Rational Numbers
Rational Numbers are the numbers that can be expressed in the form p/q where p and q are integers (q ≠ 0). It includes all natural, whole numbers, fractions and integers.
Number line or coordinate axis
rational Numbers can also be represented on a number line like integers i.e. positive rational numbers are on the right to 0 and negative rational numbers are on the left of 0.
Opposite numbers
Like integers, the additive inverse of rational numbers is also the same.
This shows that the additive inverse of 3/7 is - (3/7)
This shows that
Plotting a rational number
Basic rules of representing rational no. on number line
- If the rational no fraction is proper then, it lies between 0 and 1.
- If the rational no .fraction is improper then, we first convert it to mixed fraction and then the given rational no. lies between the whole number and next whole number.
We use following steps to represent a rational number or fraction for example, 5757 on the number line.
Step 1 − We draw a number line.
Step 2 − As the number 5757 is a positive number, it lies on the right side of zero.
Step 3 − So, after zero mark, we have 17,27,37,47,57,67,17,27,37,47,57,67, and (7777 = 1).
Step 4 − The rational number 5757 on the number line is shown as follows.
Numerator less than denominator
Let us consider 3/4 and −3/4. First, let us plot 3/4.
- Here, the numerator 3 is less than the denominator 4.
- Then the positive rational number will be between 0 and 1.
- Now, let us draw a number line and plot 1 and −1.
- Then the number 34 has to lie somewhere between 0 and 1.
- Now we divide the length between 0 and 1 into equal parts.
- The Denominator gives us the number of equal parts(4).
- It is 4, so we divide it into 4 equal parts
- The numerator tells us the number of parts starting from zero.
- Here, it is 3. So we mark the point 3 parts away from the zero as shown in the below figure
Similarly, −3/4 can be marked using the same procedure because −3/4 is the corresponding value of 34.
We know that it lies between 0 and −1. So, we divide it into four equal parts and mark 3 parts away from the zero, as shown in the below figure.
Numerator greater than denominator
Let us consider 64 and −64. First, let us plot 64.
- Here, the numerator 6 is greater than the denominator 4.
- Then, we have to convert it into a mixed fraction.
- A mixed fraction of 64 is 124.
- Now, let us draw a number line and plot 1,−1 and 2,−2.
- Then the number 124 has to lie somewhere between 1 and 2.
- Now we divide the length between 1 and 2 into equal parts.
- The Denominator gives us the number of equal parts.
- It is 4, so we divide it into 4 equal parts.
- The numerator tells us the number of parts starting from 1.
- Here, it is 2. So we mark the point 2 parts away from the 1.
Similarly, −6/4 can be marked using the same procedure because −6/4 is the corresponding value of 6/4.
We know that it lies between −1 and −2. So, we divide it into four equal parts and mark 2 parts away from the −1.